Hydraulic system for drilling rigs



, 1951 J. E. YARBOROUGH HYDRAULIC SYSTEM FOR DRILLING RIGS Oct. 30

1 u a I r 1 I \llllllll Illllllllllllllhll] p HIIIIH l!! Patented Dec. 18, 1951 UNITED STATES PATENT OFFICE HYDRAULIC SYSTEM FOR DRILLING RIGS Joel E. Yarborough, Enid, kla., assignor to The George E. Failing Supply Company, Enid, 0kla., a corporation of Oklahoma Application October 30, 1948, Serial No. 57,543

Claims. 1

This invention relates to drilling rigs such as used for drilling earth formations and of the type employing a hydraulic lift and pressure mechanism for running in and pulling pipe, controlling and applying pressure on the drill bit, and for other operations involving manipulations of the drilling string.

The principal objects of the present invention are to provide a high speed lift with a relatively small pump; to provide a hydraulic mechanism capable of holding a high pressure on the drill bit while drilling without heating of the hydraulic fluid; and to provide a hydraulic control apparatus capable of greater lifting power with a given size hydraulic mechanism.

In accomplishing these and other objects of the invention I have provided improved structure, the preferred form of which is illustrated in the accompanying drawing wherein:

Fig. 1 is a diagrammatic view of a hydraulic unit of a drilling rig and a hydraulic control apparatus therefor constructed in accordance with the present invention.

Fig. 2 is a vertical section through the pressure accumulator of the control apparatus.

Referring more in detailto the drawing:

l designates a hydraulic unit of a drilling rig such as used in rotary drilling of earth formations. Drilling units of this character usually comprise a pair of laterally spaced cylinders 2 and 3 arranged in vertical relation and connected at their upper ends by a cross head 4. Slidably mounted on the cylinders is a cross head or elevator 5 carrying the usual swivel head 6 to which a Kelly rod 1 or upper section of the drill pipe is adapted to be connected for raising and lowering the drilling string as when running in or pulling the drill pipe and controlling pressure on the drill bit (not shown) that is connected to the lower end of the drill pipe.

Reciprocably mounted in the respective cylin ders are pistons B and 9 that are connected with substantially large piston rods l9 and l l slidable through stufling boxes l2 and I3. carried as a cross head on the upper ends of the cylinders. The rods l9 and I! are interconnected by a cross head M which in turn is connected by rods [5 and I6 with the cross head 5 to effect raising and lowering thereof on the cylinders when a pressure fluid is applied on the pistons as will be well understood by those skilled. in the drilling art The pressure fluid, for example, a liquid under pressure of a pump, is admitted into the lower ends of the cylinders through branch pipes I! and I8 that are connected with a common supply pipe l9. During lifting, liquid is exhausted from the upper ends of the cylinders through branch pipes 20 and 2| that are connected by a common pipe 22. When the drilling string is lowered, the direction of the pressure liquid is reversed with the liquid being admitted through the pipes 20 and 21 and discharged from the pipes Ill and 18. The pipes l9 and 22 are interconnected by transfer pipe 23 having a control valve 24 connected therein. The pipes l9 and 22 continue from their connections with the transfer pipe 23 to connect with a storage tank 25 which contains a supply of the liquid. The pipe I9 is provided with a control valve 26 that is inserted therein intermediate the storage tank and the connection with the transfer pipe 23. The pipe 22 is also provided with a similar control valve 21 that is connected therein between the connection of the transfer pipe 23 and the branch pipes leading to the upper ends of the cylinders. Connected into the pipe 22 between the transfer pipe and the pressure cylinder is a pump 28 having an inlet connection 29 through which liquid is drawn from the tank 25 through a, connecting portion 30 of the pipe 22 and discharged through the outlet connection 3! of the pump into the pipe 22.

A bypass 32 is provided around the pump to connect the pipe 22 with the storage tank for relieving pressure in excess of a predetermined maximum as set by a pressure relief valve 33 that is connected into the bypass.

The structure thus far described is substantially conventional but to provide for high speed operation, a pump of substantially large capacity is required to provide pressure liquid in volume to produce the desired speed of operation.

In order to overcome this difficulty and at the same time provide for high speed operation with a pump of relatively small capacity, the pipe 22 is provided between the cylinders and the control valve 2'! with lateral connections 34 and 35 for a bypass 36 having leg portions 3! and 38 interconnected by a pipe 39 to which an accumulator 40 is connected through a T fitting 4!. The leg portion 31 of the bypass is provided with a choke 42 and the other leg 38 is provided with a control valve 43. Connected in the pipe 39 between the choke and the connection of the accumulator is a check valve 44 opening in the direction of the accumulator.

The accumulator 40 comprises a casing 45 of substantially cylindrical shape enclosed at the ends to provide a bladder chamber 46. Mounted in the chamber 46 is a bladder 41 that is formed of resilient material such as rubber to permit expansion thereof under a gaseous fluid such as compressed air that is admitted into the bladder through a valve connection 48. On inflation the bladder may substantially fill the casing but is adapted to be compressed by the pressure fluid admitted into the casing through a port 49 through the pipe connection 4|.

In operating the control apparatus constructed and assembled as described, the gaseous pressure fluid such as compressed air is admitted into the bladder to exert pressure on the liquid in cooperation with the pressure established by the pump 23. When the pump is in operation, liquid is drawn from the tank 25 and discharged through the pipe 22 upon opening of the valve 21 and closing of the valve 24. The liquid is then retained in the lower end of the cylinders and the flow is diverted through the choke 42 and check valve 44 into the chamber of the accumulator up to the point where the pressure on the liquid substantially balances the gaseous pressure in the bladder.

Assuming that liquid is to be admitted to the lower ends of the cylinders for raising the cross. head 5 as when lifting the drilling string, the valves 26 and 43 are closed and the valves 24 and 2i are opened. The pump then discharges liquid through the transfer pipe valve 24, through the pipe l9 and branch pipes l1 and I8 to the lower 1 ends of the cylinders to act on the pistons and effect upward movement thereof. Pressure fluid is also acting on the upper ends of the pistons through the pipe 22 and branch pipes and 2| since the valve 2! is open, however, since the area on the tops of the pistons as established by the relatively large diameter rods I0 and H is less than the area of the bottoms of the pistons, the movementv is upward. If a'high speed lift is desired, the valve v43 may be opened which allows the liquid in the accumulator to be discharged into the pipe 22 under the expansive action of the gaseous pressure medium in the bladder to supplement. the pump pressure and, increase the volume flow of liquid to the lower ends of the cylinders.

For the downstroke the valves 24: and 43 are closed and the valve 21 is opened. The valve 25 is then used as a throttling valve to control the return of the pressure fluid to the storage tank. The pressure of the pump is being applied to the upper areas of the pistons through the pipes 22, 20 and 21 during which time a portion of the liquid may be discharged through the choke and check valve into the accumulator to maintain or re-establish the liquid supply in the accumulator. Upon throttling of the valve 26, the liquid in the lower ends of the cylinders is discharged through the pipes I1 and I8 and pipe l9 into the storage tank allowing descent of the cross head 5.

During drilling operation if a hard formation highly resistant to cutting action of the bit is encountered, the valves 26 and 24 are opened and the valve 21 is closed. Then upon opening of the valve 43, the liquid stored under pressure of the bladder is immediately available to act on the pistons. This feature eliminates the usual disadvantage of a hydraulic system, that is, heating of the oil, when the pressure is applied by the pump. It is obvious that during this operation when utilizing the accumulated pressure liquid the pump is merely circulating the pressure fluid through the transfer pipe back to the storage tank.

High speed operation may be effected on the downstroke by closing the valve 24 and opening effective areas on respective ends thereof, ducts,

4 the valves 26 and 27. Assuming the accumulator is charged, the valve 43 is opened so that the liquid in the accumulator is released to supplement the pump pressure.

In the event that an exceptionally heavy load must be lifted, it is possible with the system of valves illustrated, to lift substantially twice the load that is possible with an ordinary straight lift differential control system. To accomplish this result all the valves are opened, after which valve 21 is closed and then valve 26. The liquid on top of the pistons is displaced into the accumulator and. full pump pressure is provided in the bottom of the cylinders. Since the nominal lift is accomplished with the same pressure on the top as on the bottom of the cylinder, this arrangement of valve control gives twice the area for the pump pressure to act upon. This setting is alsoimportant as with the valve setting just described, it is possible to apply double the pump pressure in the accumulator so that the accumulator is charged for effecting an exceptionally high speed. If desired, the entire system may be operated asa straight differential control system by closing the valve 43 and opening the valve 21-. By using relatively large piston rods, the control system is much faster on both the up and down stroke.

With the present system, there is no necessity of an unloader as it is possible on the downstroke to feed from the accumulator. This is efiected by closing the valve 21 and opening the valves 43, 24 and 26. With this arrangement, the pump operates under no pressure as the liquid is merely circulated from the pump through the transfer pipe back to the receiver. Thus, a pressure maybe maintained on the drill bit by means of the accumulator without. heating of the pressure liquid. The choke and check valve are important features in effecting fill of the accumulator automatically at high pressure points in the operating cycle without/giving a spongy or slack feeling of the system.

What I claim and desire to secure by Letters Patent is:

1. In combination with a hydraulic unit of a drilling rig including a cylinder, a piston in the cylinder having differential effective areas on the respective ends thereof, the combination of a reservoir for storing hydraulic medium, ducts connecting the reservoir with the respective ends of the cylinder, a pump connected in one Of the ducts, a transfer duct. interconnecting said ducts for supplying hydraulic pressure medium to the end of the cylinder having the larger effective area on the piston, a valve in the other of the first-named ducts between the transfer duct and reservoir for rendering the pump pressure effective through both ducts when said valve is closed to affect movement of the piston, valves in the duct having the pump. and the transfer duct to direct the hydraulic pressure medium from the pump to one or the other ends of the cylinder, a bypass duct connected with one of the first named ducts between the valve therein and the hydraulic unit, an accumulator connected with the bypass duct, a, control valve in the bypass duct between the accumulator and hydraulic unit, a choke in the bypass duct ahead of the accumulator, and a check valve in the bypass duct between the choke and accumulator.

2. In combination with a hydraulic unit of a drilling rig including a cylinder and a piston reciprocable in the cylinder having differential connected with the respective ends of the cylinder, means for supplying a hydraulic pressure medium to the duct that is connected with the end of the cylinder having the smaller effective piston area, said supply means having an inlet in connection with the duct that connects with the end of the cylinder having the larger effective piston area, a transfer duct interconnecting said ducts intermediate said supply means and the cylinder through which hydraulic pressure medium is supplied simultaneously to the end of the cylinder having the larger effective piston area to effect movement of the piston in one direction responsive to the difference in effective areas of the piston, a valve in the transfer duct for shutting off hydraulic pressure medium under pressure to the end of the cylinder having the larger effective piston area to effect movement of the piston in the opposite direction,an accumulator connected with the duct that connects with the end of the cylinder having the smaller effective piston area and located in said duct intermediate the transfer duct and said cylinder, a control valve between the transfer duct and the accumulator to control operational speed of the piston, a shut off valve in the duct that connects with the end of the cylinder having the larger effective piston area and located in said duct intermediate the transfer duct and the inlet of the supply means to shut off flow to the inlet of the supply means when said transfer valve is open to operate said piston in said one direction and to establish flow to the inlet of the pressure supply means when the transfer valve is closed to operate the piston in said other direction, and means for charging the accumulator from the pump responsive to movement of the piston in both of said directions.

3. In combination with a hydraulic unit of a drilling rig including a cylinder and a piston reciprocable in the cylinder having differential effective areas on respective ends thereof, ducts connected with the respective ends of the cylinder, means for supplying a hydraulic pressure medium to the duct that is connected with the 4 end of the cylinder having a smaller effective piston area, said supply means having an inlet in connection with the duct that connects with the end of the cylinder having the larger effective piston area, a transfer duct interconnecting said ducts intermediate said supply means and the cylinder through which hydraulic pressure medium is supplied simultaneously to the end of the cylinder having the larger effective piston area to effect movement of the piston in one 1 direction responsive to the difference in effective areas of the piston, a valve in the transfer duct for shutting off hydraulic pressure medium under pressure to the end of the cylinder having the larger effective piston area to effect movement of the piston in the opposite direction, an accumulator connected with the duct that connects with the end of the cylinder having the smaller effective piston area and located in said duct intermediate the transfer duct and said cylinder, a control valve between the transfer duct and the accumulator to control operational speed of the piston, a shut off valve in the duct that connects with the end of the cylinder having the larger effective piston area and located in said duct intermediate the transfer duct and the inlet of the supply means to shut off flow to the inlet of the supply means when said transfer valve is open to operate said piston in said one direction and to establish flow to the inlet of the pressure supply means when the transfer valve is closed to operate the piston in said other direction, and means for supplying the hydraulic pressure medium displaced from the end of the cylinder having the smaller piston area to the accumulator when the piston is moved in said one direction.

4.'In combination with a hydraulic unit of a drilling rig including a cylinder and a piston reciprocable in the cylinder having differential effective areas on respective ends thereof, ducts connected withthe respective ends of the cylinder, meansfor supplying a hydraulic pressure medium'to the duct that is connected with the end of the cylinder having the smaller effective piston area, said supply means having an inlet in connection with the duct that connects with the end of the cylinder having the larger effective piston area, a transfer duct interconnecting said ducts intermediate said supply means and the cylinder through which hydraulic pressure medium is supplied simultaneously to the end of the cylinder having the larger effective piston area to effect movement of the piston in one direction responsive to the difference in effective areas of the piston, a valve in the transfer duct for shutting off hydraulic pressure medium under pressure to the end of the cylinder having the larger effective piston area to effect movement of the piston in the opposite direction, a bypass duct having inlet and outlet connections with the duct that connects with the end of the cylinder having the smaller effective piston area and located in said duct intermediate the transfer duct and said cylinder, an accumulator in the bypass duct, a check valve in the inlet of the bypass duct to pass pressure medium into the accumulator, a control valve between the transfer duct and the accumulator to control operational speed of the piston, a shut off valve in the duct that connects with the end of the cylinder having the larger effective piston area and located in said duct intermediate the transfer duct and the inlet of the supply means to shut off flow to the inlet of the supply means when said transfer valve is open to operate said piston in said one direction and to establish flow to the inlet of the pressure supply means when the transfer valve is closed to operate the piston in the opposite direction, and a shut off valve in the bypass outlet to retain the pressure medium in the accumulator and to release the accumulated pressure medium when said shut off valve is opened for supplementing the pump pressure.

5. In combination with a hydraulic unit of a. drilling rig including a cylinder and a piston reciprocable in the cylinder having differential effective areas on respective ends thereof, ducts connected with the respective ends of the cylinder, means for supplying a hydraulic pressure medium to the duct that is connected. with the end of the cylinder having the smaller effective piston area, said supply means having an inlet in connection with the duct that connects with the end of the cylinder having the larger effective piston area, a transfer duct interconnecting said ducts intermediate said supply means and the cylinder through which hydraulic pressure medium is supplied simultaneously to the end of the cylinder having the larger effective piston area to effect movement of the piston in one direction responsive to the differences in effective areas of the piston, a valve in the transfer duct for shutting off hydraulic pressure medium under pres- 1 sureto the nclof thecyllntleit having the lesser f ctive piston area to efiect movement; of; the piston in the opposite direc ion, abypass duct having inlet andoutlet connections, with the duct that connects. withthe-emlofi the cylinderhaving the smaller efieotive piston area and located in said duct intermediate the transfer inch and said cylinder, an aceumulatorin the bypass duct, is check valve in the inlet Qfi'hhfi bypass. duc to pass pressure medium into the. accumu ator; a, control valve between the transfer duct and. the. accumulator to control. operational speed of: the piston a shut ofi. valvein the duo-t that. connect with the end, of. the cylinder-having the. larger efiective piston area, and located in said duet in-. termediate' the transfer duct, and the inlet of the supply means to shut. oil flow to the inlet of the supply means when said transfer. valve is, open to operate said piston in said one direction and to establish fiow to the. inlet. of the pressure supply means when the transfer valve. is closed.

to operate the piston in the. opposite direction, a

shutoff valve in the bypass outlet. to retain the.

pressureimellium in the accumulator and tore leasethe. accumulated pressure medium when said shutoff valve is opened for supplementing the. pump pressure, and a choke in the. bypass be.- tween the. check valve. and the. inlet connection thereof. with. the, bypass inlet connection.

J QEL El YARBOROUGH.

REFERENCES CITED The following references are of record in the file of this patent:

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